move mp_balance_mul to tommath_private.h
diff --git a/tommath.h b/tommath.h
index b817117..d0aec83 100644
--- a/tommath.h
+++ b/tommath.h
@@ -335,7 +335,6 @@ int mp_sub(const mp_int *a, const mp_int *b, mp_int *c);
/* c = a * b */
int mp_mul(const mp_int *a, const mp_int *b, mp_int *c);
-int mp_balance_mul(const mp_int *a, const mp_int *b, mp_int *c);
/* b = a*a */
int mp_sqr(const mp_int *a, mp_int *b);
diff --git a/tommath_private.h b/tommath_private.h
index 606ba29..c85c0c6 100644
--- a/tommath_private.h
+++ b/tommath_private.h
@@ -50,6 +50,7 @@ int fast_s_mp_mul_high_digs(const mp_int *a, const mp_int *b, mp_int *c, int dig
int s_mp_mul_high_digs(const mp_int *a, const mp_int *b, mp_int *c, int digs);
int fast_s_mp_sqr(const mp_int *a, mp_int *b);
int s_mp_sqr(const mp_int *a, mp_int *b);
+int mp_balance_mul(const mp_int *a, const mp_int *b, mp_int *c);
int mp_karatsuba_mul(const mp_int *a, const mp_int *b, mp_int *c);
int mp_toom_mul(const mp_int *a, const mp_int *b, mp_int *c);
int mp_karatsuba_sqr(const mp_int *a, mp_int *b);